System for applying uniform layer of a flowable material to a substrate

ABSTRACT

A system for dispensing and applying a uniform layer of liquid or flowable material is described. The system includes a distributor unit from which droplets of the material can be propelled by centrifugal force, and means are provided for spinning the distributor unit at relatively high rpms. The distributor unit includes a cylindrical chamber into which flowable material is received for distribution therefrom, and the cylindrical chamber is provided with annular channels associated with spaced rows of openings which penetrate the wall of the cylindrical chamber. The system is especially useful for coating lining compounds or interior surfaces of pipes.

United States Patent Kazee 1 1 March 6, 1973 1 SYSTEM FOR APPLYINGUNIFORM 2,520,397 8/1950 Green ..1 18/306 LAYER F A F O MATERIAL2,986,338 5/1961 Foster ....239/224 x TO A SUBSTRATE PrimaryExaminerJohn P. McIntosh Attorney-Cushman, Darby & Cushman [57] ABSTRACTA system for dispensing and applying a uniform layer of liquid orflowable material is described. The system includes a distributor unitfrom which droplets of the material can be propelled by centrifugalforce, and means are provided for spinning the distributor unit atrelatively high rpms. The distributor unit includes a cylindricalchamber into which flowable material is received for distributiontherefrom, and the cylindrical chamber is provided with annular channelsassociated with spaced rows of openings which penetrate the wall of thecylindrical chamber. The system is especially useful for coating liningcompounds or interior surfaces of pipes.

9 Claims, 3 Drawing Figures PATEHTEUHAR elm- 3719168 U SHEEIEUF 2 Y IINVENTOR /6 I 26 R056? 2B K0255 QRXTTORNEYJ SYSTEM FOR APPLYING UNIFORMLAYER OF A FLOWABLE MATERIAL TO A SUBSTRATE BACKGROUND AND BRIEFDESCRIPTION OF INVENTION The invention relates to a distributor systemfor applying a uniform layer of flowable material to a substratesurface. More specifically, the invention is concerned with providingfor uniform application of lining compounds, such as coal tar-epoxycompositions, onto inner surfaces of pipes, especially concrete pipes.The system provides for an optimization of centrifugal forces in aspinning distributor unit so as to achieve very carefully controlledcoating and penetration of a substrate.

It is known in this art to provide for various forms of spraying devicesand spinning devices which are capable of injecting or applying a liquidspray to the interior of a pipe or onto another surface. Typically,prior art devices have provided for such things as spray nozzles andspinning distributor heads which receive a supply of liquid fordispensing onto a surface. The various spinning head arrangements whichhave been tried are very often complex and of such design as to requirefrequent cleaning and other maintenance, thereby resulting in unwantedshutdown time for the dispensing system. Furthermore, there has been aproblem with prior art applicators of producing localized buildup,lumping or sagging of certain lining materials which are typicallyapplied to inner surfaces of concrete pipes. Known distributor systemsare shown and described, for example, in U.S. Pat. Nos. 2,185,570;2,303,088;

3,017,116; 3,034,729; 3,180,312; 3,197,143, and in German Pat. 373,724and French Pat. 361,840.

The present invention provides for improvements in systems of the typein which a flowable material is carried from a source to a rotatingdistributor unit for being propelled from the distributor unit onto aninner surface of a pipe or other surface. Rotation of the distributorunit causes the material to be subjected to centrifugal forces whichpropel droplets of the material through rows of spaced openings providedthrough a cylindrical wall portion of the distributor unit. Preferablymore than one row of openings are provided along the length of thedistributor unit so that there is an overlapping of thin coating layersonto a substrate as the spinning distributor unit is moved relative tothe substrate. In order to optimize and control the force and velocityto which individual droplets are subjected, annular channel means areformed into the inner wall surface of the distributor unit forchanneling a reservoir of the flowable material behind the spacedopenings. Typically, the spaced openings are arranged in a plurality ofrows positioned axially along the distributor unit, and a correspondingnumber of annular channel means are formed in association with the rowsto provide an annular reservoir behind each row of openings. Inaddition, all interior surfaces of the distributor unit are smooth sothat there is an uninterrupted and easy flow of material across theinner wall of the distributor unit and into each of the annularchannels. This provision for a reservoir of flowable material behindeach opening not only assists in increasing the velocity of movement ofdroplets of materials through the openings, but also assures a uniformsupply of material for all of the openings of the distributor unit sothat a uniform application of material can be achieved.

Means are provided for spinning the distributor unit at a relativelyhigh speed, for example, in the range of 15,000 to 25,000 rpms, andpreferably around 20,000

to 23,000 rpms. However, speeds up to 45,000 rpms may be used with moreviscous materials to obtain good atomization and continuous filmcoverage of the material. This represents a substantially higher rate ofspinning than has been utilized with many known prior art devices ofthis type. The relatively high spinning rate and the provision forannular reservoir channels within the distributor unit itself bothcontribute to better distribution characteristics of droplets offlowable material from the distributor unit. Individual droplets arepropelled at relatively high velocities which are subject to carefulcontrol, and as a result, very precise and uniform coating (andpenetration, where desired) can be achieved in the application of alining material to the interior of a pipe.

In a preferred embodiment, the system of this invention provides for aconduit means which carries flowable material from a source into adistributor unit which receives and subjects the material to centrifugalforces. The conduit means dumps material directly into the distributorunit without a requirement for deflecting devices or other collateralstructures. The distributor unit has a chamber for receiving thematerial, and the chamber is defined by a cylindrical sleeve means whichis closed at one end and which is at least partially open at an oppositeend so as to receive a continuous supply of the material from theconduit means. The cylindrical sleeve means has a plurality of rows ofspaced openings formed radially therethrough for releasing droplets ofthe material from the chamber of the distributor unit when the materialis subjected to centrifugal forces. Annular channel means are formedinto the inner wall surface of the cylindrical sleeve means forchanneling a reservoir of the material behind the spaced openings ineach of the rows of such openings. The rows of spaced openings arelocated at the bottoms of their respective channels so that each dropletof material will be subjected to the same head of liquid pressure andwill travel through the same wall thickness of the cylindrical sleeve.Means for subjecting the material to centrifugal forces may comprise amotor means, operated by a pneumatic drive, for spinning the distributorunit about its central longitudinal axis. Preferably, spinning ismaintained at constant level, between about 20,000 to 45,000 rpms,during application of material to a substrate.

The system of the present invention may be combined with knownstructures for moving the distributor unit in either a horizontal orvertical path for coating a pipe interior, or other substrate, as itmoves along the path. Preferably a greater number of dispensing openingsare provided in a trailing row, than in a leading row, of such openingsin the distributor unit so that there is an initial wetting of thesurface, followed by a heavier layer of the coating material. Typically,the system may be used for applying flowable materials which are usefulin lining cured or uncured cement or ceramic pipes, or cast metal pipes,with coal tar solution (with no epoxy resin), epoxy resin compositions,and coal tar-epoxy resin combinations. Very uniform and satisfactorylining layers can be applied withthicknesses controlled in the range of16 to 40 mils or whatever thickness is desired. Pipes provided with suchlinings are typically used in sanitary sewer applications.

These and other advantages and features of the present invention willbecome apparent in the more detailed discussion which follows, and inthat discussion reference will be made to the accompanying drawings asbriefly described below.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic representation of adistributor system of the type contemplated by this invention as shownin use for coating the interior of a pipe (shown in section);

FIG. 2 is an elevational view, partly in cross section, of a distributorunit construction utilized in the system of the present invention; and

FIG. 3 is a perspective view of a coupling arrangement provided forassembling the distributor unit and motor portion of the system to arelatively long conduit means.

DETAILED DESCRIPTION OF INVENTION Referring to FIG. 1, the system of thepresent invention is illustrated with reference to an operation forcoating the interior of a horizontally disposed pipe 10. The FIG. 1illustration is schematic and is not intended to illustrate relativesizes and proportions. For example, the diameter of the pipe which isbeing coated by the system may be much greater than that shown, ascompared to the diameter of a spinning distributor unit 12 associatedwith the system. Also, the system may be utilized in operations whereinthe pipe 10 is vertically disposed rather than horizontally disposed asillustrated in FIG. 1.

In operation, the system provides for an airless application of a liningor'coating material to the interior wall surface of a pipe 10. Flowablematerial is fed to a distributor unit 12 by way of a conduit means 14communicating with a source of supply for the flowable material. Theconduit means 14 introduces the flowable material directly into achamber defined within the distributor unit 12. From there, the flowablematerial is propelled outwardly from I the distributor unit 12 throughthe two rows of openings 16 which are shown in the example of FIG. 1.Motor means (not shown) are provided for spinning the distributor unit12 about its central longitudinal axis to thereby subject the flowablematerial to centrifugal forces. As the distributor unit 12 is rotatedrapidly about its axis, it is also moved axially along the length of thepipe, or other article, to be coated. Any known carriage and centeringmeans 18 may be provided for allowing a sliding or rolling movement ofthe distributor unit 12 and its associated structures, through theinterior of the pipe. The distributor unit 12 is moved toward the rightin the FIG. 1 view during a coating operation. The distributor unit 12is mounted or carried at the end of a relatively long condu it means 20which functions as a carrier and support for the spinning distributorunit 12 as it passes through the hollow interior of a pipe.

FIG. 2 illustrates, in enlarged scale, details of the distributor unit12 and its associated structures. The distributor unit 12 which is shownin FIG. 2 is viewed in a vertical attitude as contrasted with thehorizontal attitude of the unit of FIG. 1. Basically, the distributorunit comprises a cylindrical sleeve means having a closed end so as todefine a generally cylindrical chamber within the distributor unit forreceiving flowable material from the conduit means 14. As shown, theconduit means 14 is provided with a one-way ball valve structure '22,which opens when flowable material is fed from a source of supply, andwhich closes when feeding is stopped (by control means not shown). Aterminal end 24 of the conduit means 14 is positioned within thecylindrical chamber of the distributor unit so as to introduce flowablematerial directly into the chamber without interruption in its flow. Allinner surfaces of the chamber are relatively smooth, and thus, thematerial can flow about the entire periphery of the chamber withoutinterruption and without the use of deflectors or other guiding devices.In the arrangement shown, flowable material would contact a closed endwall portion 26 of the distributor unit while the unit is being rotatedat a relatively high speed. From there, the material would flow radiallyoutwardly to thecylindrical wall portion of the chamber and wouldcollect'in annular channel means 28 formed into the inner cylindricalwall surface of the chamber.

The annular channel means function as reservoirs for holding acontinuous supply of flowable material behind a plurality of spacedopenings 16 formed through the cylindrical wall of the distributor unit.In addition, the annular channel means provide for a pressure head offlowable material behind each spaced-opening 16 so that the effect ofcentrifugal forces on the flowable material will be optimized forpropelling the material outwardly from the distributor unit. In thepreferred arrangement, a single row of spaced openings 16 is associatedwith a single annular channel means 28 so that each spaced opening 16can be placed at the bottom of its associated channel. This assures aknown and identical pressure head of flowable material behind eachspaced opening of a given annular channel, and assures that each dropletof material will travel for the same distance through the thickness ofthe wall of the cylindrical sleeve portion of the distributor unit.

Any known means may be provided for subjecting the flowable material inthe distributor unit 12 to centrifugal forces so as to force thematerial out of the distributor unit chamber and onto a substrate. Inthe illustrated embodiment, an air motor means 30 of known constructionis utilized for driving the distributor unit 12. This is accomplished bymounting the distributor unit 12 on a drive shaft 32 of the motor means30 so that the distributor unit 12 will be rotated about its centrallongitudinal axis. It can be seen that the end 26 of the distributorunit 12 is essentially a closed end structure, but an opening can beprovided through its center at 34 for receiving a fastening bolt whichsecures the distributor unit 12 to the drive shaft 32 of the motor means30. The motor means 30 is preferably an air motor of known construction,and air is supplied to and returned from the motor means 30 by coaxialhoses 36 and 38, respectively. It is important to provide for an airreturn with the hose 38 to prevent contamination of a freshly appliedcoating by moisture or lubricant that may be carried in the air stream.Also, if the air were allowed to exhaust in the area of the distributorit could fall onto a freshly applied film, causing a multiple filmeffect with delamination problems. This provides for an integralstructure for the distributor unit 12 and its motor means 30 which canbe easily connected and disconnected from an air supply system carriedwithin the conduit 20.

FIG. 3 illustrates a coupling assembly which may be utilized forsecuring the distributor unit 12 and its motor means 30 to the carrierconduit 20. As shown, the carrier conduit is provided with a rigid endstructure, in the form of a sleeve, for receiving the cylindrical shapeof the motor 30 and for connecting the motor 30 to its air supply systemcontained within the conduit 20. Once the motor means 30 and itsattached distributor unit 12 are in position, a fastening band 40 (seeFIG. 2) is secured around the assembled structures to maintain them inposition. The conduit 20 may be of a rigid construction throughout itsentire length, or it may be flexible wherever desired.

As an example of a typical construction for the distributor unit, thechamber of the unit is formed from two basic subassemblies. A firstsubassembly having the closed end wall 26 and an opposite open end canbe manufactured from aluminum and provided with a central bore 34 formounting the unit to the drive shaft of a motor means. This subassemblyis formed with an outside diameter of approximately 5 inches and with aminimum inside diameter of 4.250 inches. Annular channels 28 are formedto a depth of approximately 3/32 inches outwardly from the minimuminside diameter of the subassembly, and openings 16 are drilled with1/16 inch diameters. Preferably, the openings 16 are equally spacedapart in their respective rows, and twice as many openings are providedin the trailing row (at the lower end of FIG. 2) as compared with theleading row (the upper row in FIG. 2). For example, 18 equally spacedopenings 16 may be provided in the upper row, and 36 equally spacedopenings may be provided in the bottom row. This provides for an initialwetting of a pipe interior by the leading row as the distributor unit ismoved axially through the pipe; followed by an overlapping coating layerapplied by the greater number of openings in the trailing row.

In the example construction, a second subassembly 50 is formed fromaluminum for attachment to the open end of the first subassembly. Thesubassembly 50 functions to partially close the open end of the firstsubassembly so that a certain amount of overfilling of the annularreservoirs 28 and of the chamber of the distributor unit can be achievedwithout danger of spilling of flowable material from the unit.Basically, the second subassembly 50 is provided with an annular lip forattachment to the open end of the first subassembly together with adepending sleeve 52 which functions to contain flowable material withinthe unit while it is spinning. The sleeve portion 52 is of a diameterwhich permits entry of the conduit 14 into the chamber defined withinthe distributor unit 12.

The above-described system provides for very excellent control overthickness and uniformity of coating of pipe interiors. Very thin coatingcan be accomplished with no localized lumping or sagging of the lining.

Although the system of the present invention may be used in applying avariety of liquid and flowable coating materials and paints, it isespecially useful for applying coal tar-epoxy coatings of variouscompositions. Coatings of this type are described, for example, in US.Pat. Nos. 2,765,288; 2,889,305 and 3,976,256. Other compositions of thistype provide for certain co-reacting polyamide resins with an aromatictertiary polyamine catalysLThe coating compositions may be applied tocured or uncured concrete pipe with the system of the present invention,and penetration and uniformity of coating application and attachment areexceptionally good. The system may be utilized manually (by holding thedistributor unit at the end of its carrier conduit 20 by hand) or withadditional structure for supporting and guiding the unit, as is known inthis art. Coatings may be applied to uncured pipe, and the coatedproduct may be subjected to kiln drying for curing of the pipe andsetting of the coating.

Having described the basic features and relationships of the invention,it can be appreciated that certain equivalent structures and designs maybe substituted for those described herein. Equivalent substitutions ofthis type are intended to be included in the scope of protection definedin the claims that follow.

What is claimed is:

l. A'system for applying a uniform layer of a flowable material to asubstrate comprising the combination of a source of flowable materialand a conduit means for carrying the material from the source to adistributor unit which receives said material and sub jects the materialto centrifugal forces,

a distributor unit for propelling droplets of spray of said materialonto a substrate which is to be coated, said distributor unit having achamber defined by a cylindrical sleeve means which is closed at one endand which is arranged to receive a continuous supply of said material,said cylindrical sleeve means having a plurality of rows of spacedopenings formed radially therethrough and opening into said chamber forreleasing droplets of said material from said chamber when the materialis subjected to centrifugal forces, and annular channel means formedinto the inner wall surface of said cylindrical sleeve means and openinginto said chamber for channeling a reservoir of said material behindsaid spaced openings in each of the rows, with one such channel meansbeing associated with each of said rows of spaced openings, to therebyincrease the velocity of movement of droplets of spray from saiddistributor unit when centrifugal forces are applied to the liquidmaterial being propelled therefrom, and

means for subjecting said material to centrifugal forces for forcing thematerial out of the chamber and through the spaced openings formedthrough the cylindrical sleeve means.

2. The system of claim 1 wherein said means for subjecting the materialto centrifugal forces comprises a motor means connected to saiddistributor unit for spinning the distributor unit about the centrallongitudinal axis of its cylindrical sleeve means.

3. The system of claim 2 wherein said motor means comprises a motoroperated by air pressure, said motor means having a drive shaft meansconnected to the closed end of the cylindrical sleeve means of saiddistributor unit.

4. The system of claim 2 wherein said motor means is capable of spinningsaid distributor unit at between about 20,000 rpms and 45,000 rpms.

5. The system of claim 1 wherein said cylindrical sleeve means of saiddistributor unit is partially closed at its end opposite to said closedend so that said flowable material can occupy space around the entireinner wall surface of said cylindrical sleeve means without spilling outfrom said partially closed end.

6. The system of claim 1 wherein said distributor unit is carried at theend of a relatively long conduit means which provides for insertion andmovement of the distributor unit into and through a hollow pipestructure so that flowable material can be applied to the interior ofthe hollow pipe structure.

7. The system of claim 6 wherein said relatively long conduit meanscontains and supports an air delivery system for operating said motormeans.

8. The system of claim 1 wherein said distributor unit is assembled fromtwo basic subassemblies comprising a first subassembly in the form of asleeve having an end which is closed and an opposite end which is open,together with a second subassembly which can be secured to said open endof said first subassembly for partially closing the open end thereof.

9. The system of claim 1 wherein there are two rows of spaced openingsin said distributor unit, and wherein there are a greater number ofopenings in one of said rows than in the other, said greater number ofopenings being in the row which is in a trailing position as thedistributor unit is moved axially relative to a surface being coated.

1' I? t II

1. A system for applying a uniform layer of a flowable material to asubstrate comprising the combination of a source of flowable materialand a conduit means for carrying the material from the source to adistributor unit which receives said material and subjects the materialto centrifugal forces, a distributor unit for propelling droplets ofspray of said material onto a substrate which is to be coated, saiddistributor unit having a chamber defined by a cylindrical sleeve meanswhich is closed at one end and which is arranged to receive a continuoussupply of said material, said cylindrical sleeve means having aplurality of rows of spaced openings formed radially therethrough andopening into said chamber for releasing droplets of said material fromsaid chamber when the material is subjected to centrifugal forces, andannular channel means formed into the inner wall surface of saidcylindrical sleeve means and opening into said chamber for channeling areservoir of said material behind said spaced openings in each of therows, with one such channel means being associated with each of saidrows of spaced openings, to thereby increase the velocity of movement ofdroplets of spray from said distributor unit when centrifugal forces areapplied to the liquid material being propelled therefrom, and means forsubjecting said material to centrifugal forces for forcing the materialout of the chamber and through the spaced openings formed through thecylindrical sleeve means.
 1. A system for applying a uniform layer of aflowable material to a substrate comprising the combination of a sourceof flowable material and a conduit means for carrying the material fromthe source to a distributor unit which receives said material andsubjects the material to centrifugal forces, a distributor unit forpropelling droplets of spray of said material onto a substrate which isto be coated, said distributor unit having a chamber defined by acylindrical sleeve means which is closed at one end and which isarranged to receive a continuous supply of said material, saidcylindrical sleeve means having a plurality of rows of spaced openingsformed radially therethrough and opening into said chamber for releasingdroplets of said material from said chamber when the material issubjected to centrifugal forces, and annular channel means formed intothe inner wall surface of said cylindrical sleeve means and opening intosaid chamber for channeling a reservoir of said material behind saidspaced openings in each of the rows, with one such channel means beingassociated with each of said rows of spaced openings, to therebyincrease the velocity of movement of droplets of spray from saiddistributor unit when centrifugal forces are applied to the liquidmaterial being propelled therefrom, and means for subjecting saidmaterial to centrifugal forces for forcing the material out of thechamber and through the spaced openings formed through the cylindricalsleeve means.
 2. The system of claim 1 wherein said means for subjectingthe material to centrifugal forces comprises a motor means connected tosaid distributor unit for spinning the distributor unit about thecentral longitudinal axis of its cylindrical sleeve means.
 3. The systemof claim 2 wherein said motor means comprises a motor operated by airpressure, said motor means having a drive shaft means connected to theclosed end of the cylindrical sleeve means of said distributor unit. 4.The system of claim 2 wherein said motor means is capable of spinningsaid distributor unit at between about 20,000 rpms and 45,000 rpms. 5.The system of claim 1 wherein said cylindrical sleeve means of saiddistributor unit is partially closed at its end opposite to said closedend so that said flowable material can occupy space around the entireinner wall surface of said cylindrical sleeve means without spilling outfrom said partially closed end.
 6. The system of claim 1 wherein saiddistributor unit is carried at the end of a relatively long conduitmeans which provides for insertion and movement of the distributor unitinto and through a hollow pipe structure so that flowable material canbe applied to the interior of the hollow pipe structure.
 7. The systemof claim 6 wherein said relatively long conduit means contains andsupports an air delivery system for operating said motor means.
 8. Thesystem of claim 1 wherein said distributor unit is assembled from twobasic subassemblies comprising a first subassembly in the form of asleeve having an end which is closed and an opposite end which is open,together with a second subassembly which can be secured to said open endof said first subassembly for partially closing the open end thereof.